Since his retirement, he still broods over not winning more European trophies in his spell at Old Trafford, singling out one semi-final against Bayer Leverkusen, where United were knocked out on away goals, denying the Scotsman and United a final against Real Madrid in the Scotsman's hometown, at Hampden Park, Glasgow.

Speaking at the launch of Glasgow's logo, marking their participation as one of the hosts of Euro 2020, Ferguson revealed his biggest regret in his career at United was not making the UEFA Champions League final of 2002. “The whole build-up was about getting to the final in Glasgow, but we lost the semi-final to Leverkusen. We were a bit unlucky, we ran out of time.”

He went on to add, “In the build-up to the final at Hampden, I was told to go up to Glasgow and check out hotels," the 74-year-old said.

"So I went up and checked out hotels that would have been ideal for us. I was driving back from Glasgow and I said: 'I don't like it, why have I done this?' And then we lost the semi-final, but that's life."

The Leverkusen side consisted of players like Michael Ballack and Dimitar Berbatov, held United to a 2-2 draw at Old Trafford, taking two valuable away goals to the second leg at home. Roy Keane put the visitors in front in the away leg, before a late Oliver Neuville equaliser titled the tie in favour of the Germans, who went on to make the final on away goals. The German team would eventually lose to Real Madrid in the final.

However, the Scot did go on to win another Champions League with Manchester United in 2008, defeating Premier League rivals Chelsea, in a penalty shootout, after the game ended in a 1-1 draw.

With the Champions League trophies he's won at the club along with the number of other honours he's picked up in his illustrious career, Sir Alex Ferguson will go down in history, as one of the greatest managers of all time.